n an alternate universe where monsters, wizards, and medieval-style swashbuckling coexists with marijuana and 21st century curse words, live two princes. Thadeous (Danny McBride) is lazy, cowardly, arrogant, and generally very unpleasant for a pothead slacker. His older brother, Fabious (James Franco), is, on the other hand, a more or less standard-issue fantasy prince. Good to the point of absurdity, Fabious can think only the best thoughts of his older-looking younger brother – even when Thadeous skips out as the best man at his planned wedding to Belladonna (Zooey Deschanel), a lovely waif with a good singing voice that Fabious has rescued.

Before the prince and his betrothed can be wed, however, the maiden is kidnapped by Leezar (Justin Theroux), an evil and seriously immature momma's boy wizard whose vile plans require deflowering two virgins – one being Belladonna and the other being Leezar – and impregnating the former maiden with demonic dragon offspring. Honorable King Tallious (Charles Dance) forces the unwilling Thadeous to accompany his brother on the quest to rescue Belladonna, which predictably goes from bad to worse. The worm doesn't begin to turn until the brothers encounter Isabel (Natalie Portman), a super-warrior who repeatedly saves the day and upon whom Thadeous immediately sets his romantic eye. Hard to blame her for not being too interested.

"Your Highness" has gotten a lot of grief from critics in early reviews. Salon's Andrew O'Hehir even asks himself if it's the worst movie ever made. I'd rather not have whatever it is that he's smoking, but it's true that, as sophomoric doper comedies and variations on road movies go, this is not quite primo. For one thing, the film gets off on the wrong foot by failing to realize that simply having characters dressed in medieval garb and saying "fuck" and "shit" mixed in with quasi-archaic dialogue isn't instantly funny or even actually a joke. Done with a bit of cleverness or enough acting panache, that kind of thing can work, but it takes a while before the performances and dialogue seem to improve. Once it does, it's pretty funny. (Even O'Hehir got a kick out of Justin Theroux's use of the term "the Fuckening.")

A worse problem is our leading man. Danny McBride has been acceptable to good in supporting roles in movies like "Pineapple Express" and "Up in the Air," but he's generally not very engaging or likable, especially in a leading role. Doing a deliberately half-baked English accent, he comes across a bit like Rowan Atkinson's conniving Black Adder by way of classic-era Bob Hope but is never as funny or enjoyably beneath contempt as his predecessors. He does get better as the film goes along, however. There's also a borderline-excessive level of violent gross-out humor here. A not-bad joke involving a severed Minotaur penis as a trophy remains on visual display far too long for my taste, but your gruesome visual dick joke mileage may vary. So, that's the bad news.

The good news is that actor-screenwriter McBride and his regular collaborator, Ben Best, are reasonably good at coming up with strong comic ideas, as fans of their other film and television work will remind us. Fortunately, they've surrounded their extremely uneven work here with some pretty amazing talent in the directing and acting departments.

We'll start with the acting. Humor has always been one of James Franco's strongest suits and he has no end of fun here spoofing the kind of uni-dimensional handsome guy parts he's largely managed to avoid up to now. It's a long wait for the movie's other costar, Natalie Portman, to show up, but when she does, she handles her duties remarkably well. I admit to being somewhat puzzled by the massive, Oscar-producing acclaim for her work in the overwrought "Black Swan," but here she provides a dead-on earnest, and therefore extremely funny, reading of her ferociously serious leading lady. If only they gave Academy Awards for stoner comedies.

As good as Portman is, however, I agree with O'Hehir that the funniest thing about "Your Highness" is its villain. Justin Theroux takes the idea of a 19-year-old evil wizard with the mentality of a precocious and ill-tempered 12-year-old and the face and white-streaked hair of a 35-year-old stock baddie, and makes the most of it. With a syrupy accent right out of a studio backlot, his performance is a small comic gem and definitely helped push the movie from "meh" to "not bad" territory for me. Almost as good is young English television actor Rasmus Hardiker, who has few lines but is nearly always onscreen. Hardiker clearly has a way with physical comedy and the comedic uses of overplaying and underplaying as Thadeous's unaccountably loyal jester-esque flunky, Courtney. As a much more treacherous servant, the ubiquitous Toby Jones is wasted in a not-funny one-joke role.

Director David Gordon Green gets, I think, the lion's share of the credit for making "Your Highness" work to the degree that it does. The film looks deliberately cheesy, but also kind of nifty-cool in a Brothers Hildebrand kind of way, and the monsters have a fun, Harryhausen-esque quality. Green also gets good performances from almost everyone and ensures that "Your Highness" never becomes boring, despite the languorous pace he's employed before. The Texas-bred director does a superb job of making the most of a script that needed some serious punching up, even to the point where we almost buy a nearly unmotivated reversal in Thadeous's character in the last act.

I'm probably some variety of super-Philistine for preferring Green's recent work to his breakthrough art house sensation, "George Washington," but then I'm usually turned off by neorealism and kind of enjoy certain slightly smart dumb comedies. I'm not necessarily saying "Your Highness" is better than "Washington" – just that I spent less time thinking about my next meal while watching it.

Single-Disc Blu-ray Review:

Universal typically does a great of including lots of bonus material on their comedies, and “Your Highness” is no exception. In addition to an entertaining audio commentary with director David Gordon Green, co-writer/star Danny McBride, and actors James Franco and Justin Theroux, the Blu-ray includes a collection of deleted and extended scenes, a 30-minute making-of featurette (“Damn You Gods!”), and the always funny Line-O-Rama. There’s also a short gag reel, additional footage from Thadeous and Fabious’ visit to the Great Wise Wizard, and a digital copy of the film.